- 1 x 2kg/41⁄2lb shoulder of lamb
- Salt and freshly ground black pepper
- 1⁄2-1 tbsp olive oil
- 2 medium onions, peeled and roughly chopped
- 1 bulb of garlic, peeled and cut in half horizontally
- Sprigs of fresh rosemary and thyme
- 400ml/14fl oz white wine
- 2 medium onions, peeled and thinly sliced then cooked in a little butter
- 4 large potatoes, peeled and thinly sliced
Preheat the oven to 110°C, 225°F, Gas 1⁄4.
Season the lamb well with salt and freshly ground black pepper.
Heat the oil in a roasting tray over a medium heat on the hob. Add the lamb and brown on all sides. Add the onions, garlic and herbs and cook to lightly brown the onion and garlic. Remove everything from the roasting tray and set aside. Pour the wine into the tray and scrape the pan with a wooden spoon to dislodge any deposits. Return the lamb and vegetables to the tray, cover tightly with foil and transfer to the oven for 1 hour.
Remove the foil and add enough water to have about 1cm/1/2in of liquid in the tray. Continue to cook, uncovered, for 5 hours, adding more water as necessary to baste the lamb joint.
Remove the lamb from the tray, strain any liquid through a sieve and reserve. Discard the herbs and vegetables. Increase the oven temperature to 150°C, 275°F, Gas 1.
To make the boulangere, spread the cooked onion slices over the base of the roasting tray, then arrange the potato slices on top, overlapping as you go. Place the lamb on top, pour the reserved liquid over the lamb and add more water till the potatoes are just covered. Place back in the oven for 2 hours, basting the lamb and potatoes occasionally.